1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2 | /* |
3 | * net/sched/act_skbmod.c skb data modifier |
4 | * |
5 | * Copyright (c) 2016 Jamal Hadi Salim <jhs@mojatatu.com> |
6 | */ |
7 | |
8 | #include <linux/module.h> |
9 | #include <linux/if_arp.h> |
10 | #include <linux/init.h> |
11 | #include <linux/kernel.h> |
12 | #include <linux/skbuff.h> |
13 | #include <linux/rtnetlink.h> |
14 | #include <net/inet_ecn.h> |
15 | #include <net/netlink.h> |
16 | #include <net/pkt_sched.h> |
17 | #include <net/pkt_cls.h> |
18 | #include <net/tc_wrapper.h> |
19 | |
20 | #include <linux/tc_act/tc_skbmod.h> |
21 | #include <net/tc_act/tc_skbmod.h> |
22 | |
23 | static struct tc_action_ops act_skbmod_ops; |
24 | |
25 | TC_INDIRECT_SCOPE int tcf_skbmod_act(struct sk_buff *skb, |
26 | const struct tc_action *a, |
27 | struct tcf_result *res) |
28 | { |
29 | struct tcf_skbmod *d = to_skbmod(a); |
30 | int action, max_edit_len, err; |
31 | struct tcf_skbmod_params *p; |
32 | u64 flags; |
33 | |
34 | tcf_lastuse_update(tm: &d->tcf_tm); |
35 | bstats_update(this_cpu_ptr(d->common.cpu_bstats), skb); |
36 | |
37 | action = READ_ONCE(d->tcf_action); |
38 | if (unlikely(action == TC_ACT_SHOT)) |
39 | goto drop; |
40 | |
41 | max_edit_len = skb_mac_header_len(skb); |
42 | p = rcu_dereference_bh(d->skbmod_p); |
43 | flags = p->flags; |
44 | |
45 | /* tcf_skbmod_init() guarantees "flags" to be one of the following: |
46 | * 1. a combination of SKBMOD_F_{DMAC,SMAC,ETYPE} |
47 | * 2. SKBMOD_F_SWAPMAC |
48 | * 3. SKBMOD_F_ECN |
49 | * SKBMOD_F_ECN only works with IP packets; all other flags only work with Ethernet |
50 | * packets. |
51 | */ |
52 | if (flags == SKBMOD_F_ECN) { |
53 | switch (skb_protocol(skb, skip_vlan: true)) { |
54 | case cpu_to_be16(ETH_P_IP): |
55 | case cpu_to_be16(ETH_P_IPV6): |
56 | max_edit_len += skb_network_header_len(skb); |
57 | break; |
58 | default: |
59 | goto out; |
60 | } |
61 | } else if (!skb->dev || skb->dev->type != ARPHRD_ETHER) { |
62 | goto out; |
63 | } |
64 | |
65 | err = skb_ensure_writable(skb, write_len: max_edit_len); |
66 | if (unlikely(err)) /* best policy is to drop on the floor */ |
67 | goto drop; |
68 | |
69 | if (flags & SKBMOD_F_DMAC) |
70 | ether_addr_copy(dst: eth_hdr(skb)->h_dest, src: p->eth_dst); |
71 | if (flags & SKBMOD_F_SMAC) |
72 | ether_addr_copy(dst: eth_hdr(skb)->h_source, src: p->eth_src); |
73 | if (flags & SKBMOD_F_ETYPE) |
74 | eth_hdr(skb)->h_proto = p->eth_type; |
75 | |
76 | if (flags & SKBMOD_F_SWAPMAC) { |
77 | u16 tmpaddr[ETH_ALEN / 2]; /* ether_addr_copy() requirement */ |
78 | /*XXX: I am sure we can come up with more efficient swapping*/ |
79 | ether_addr_copy(dst: (u8 *)tmpaddr, src: eth_hdr(skb)->h_dest); |
80 | ether_addr_copy(dst: eth_hdr(skb)->h_dest, src: eth_hdr(skb)->h_source); |
81 | ether_addr_copy(dst: eth_hdr(skb)->h_source, src: (u8 *)tmpaddr); |
82 | } |
83 | |
84 | if (flags & SKBMOD_F_ECN) |
85 | INET_ECN_set_ce(skb); |
86 | |
87 | out: |
88 | return action; |
89 | |
90 | drop: |
91 | qstats_overlimit_inc(this_cpu_ptr(d->common.cpu_qstats)); |
92 | return TC_ACT_SHOT; |
93 | } |
94 | |
95 | static const struct nla_policy skbmod_policy[TCA_SKBMOD_MAX + 1] = { |
96 | [TCA_SKBMOD_PARMS] = { .len = sizeof(struct tc_skbmod) }, |
97 | [TCA_SKBMOD_DMAC] = { .len = ETH_ALEN }, |
98 | [TCA_SKBMOD_SMAC] = { .len = ETH_ALEN }, |
99 | [TCA_SKBMOD_ETYPE] = { .type = NLA_U16 }, |
100 | }; |
101 | |
102 | static int tcf_skbmod_init(struct net *net, struct nlattr *nla, |
103 | struct nlattr *est, struct tc_action **a, |
104 | struct tcf_proto *tp, u32 flags, |
105 | struct netlink_ext_ack *extack) |
106 | { |
107 | struct tc_action_net *tn = net_generic(net, id: act_skbmod_ops.net_id); |
108 | bool ovr = flags & TCA_ACT_FLAGS_REPLACE; |
109 | bool bind = flags & TCA_ACT_FLAGS_BIND; |
110 | struct nlattr *tb[TCA_SKBMOD_MAX + 1]; |
111 | struct tcf_skbmod_params *p, *p_old; |
112 | struct tcf_chain *goto_ch = NULL; |
113 | struct tc_skbmod *parm; |
114 | u32 lflags = 0, index; |
115 | struct tcf_skbmod *d; |
116 | bool exists = false; |
117 | u8 *daddr = NULL; |
118 | u8 *saddr = NULL; |
119 | u16 eth_type = 0; |
120 | int ret = 0, err; |
121 | |
122 | if (!nla) |
123 | return -EINVAL; |
124 | |
125 | err = nla_parse_nested_deprecated(tb, TCA_SKBMOD_MAX, nla, |
126 | policy: skbmod_policy, NULL); |
127 | if (err < 0) |
128 | return err; |
129 | |
130 | if (!tb[TCA_SKBMOD_PARMS]) |
131 | return -EINVAL; |
132 | |
133 | if (tb[TCA_SKBMOD_DMAC]) { |
134 | daddr = nla_data(nla: tb[TCA_SKBMOD_DMAC]); |
135 | lflags |= SKBMOD_F_DMAC; |
136 | } |
137 | |
138 | if (tb[TCA_SKBMOD_SMAC]) { |
139 | saddr = nla_data(nla: tb[TCA_SKBMOD_SMAC]); |
140 | lflags |= SKBMOD_F_SMAC; |
141 | } |
142 | |
143 | if (tb[TCA_SKBMOD_ETYPE]) { |
144 | eth_type = nla_get_u16(nla: tb[TCA_SKBMOD_ETYPE]); |
145 | lflags |= SKBMOD_F_ETYPE; |
146 | } |
147 | |
148 | parm = nla_data(nla: tb[TCA_SKBMOD_PARMS]); |
149 | index = parm->index; |
150 | if (parm->flags & SKBMOD_F_SWAPMAC) |
151 | lflags = SKBMOD_F_SWAPMAC; |
152 | if (parm->flags & SKBMOD_F_ECN) |
153 | lflags = SKBMOD_F_ECN; |
154 | |
155 | err = tcf_idr_check_alloc(tn, index: &index, a, bind); |
156 | if (err < 0) |
157 | return err; |
158 | exists = err; |
159 | if (exists && bind) |
160 | return 0; |
161 | |
162 | if (!lflags) { |
163 | if (exists) |
164 | tcf_idr_release(a: *a, bind); |
165 | else |
166 | tcf_idr_cleanup(tn, index); |
167 | return -EINVAL; |
168 | } |
169 | |
170 | if (!exists) { |
171 | ret = tcf_idr_create(tn, index, est, a, |
172 | ops: &act_skbmod_ops, bind, cpustats: true, flags); |
173 | if (ret) { |
174 | tcf_idr_cleanup(tn, index); |
175 | return ret; |
176 | } |
177 | |
178 | ret = ACT_P_CREATED; |
179 | } else if (!ovr) { |
180 | tcf_idr_release(a: *a, bind); |
181 | return -EEXIST; |
182 | } |
183 | err = tcf_action_check_ctrlact(action: parm->action, tp, handle: &goto_ch, newchain: extack); |
184 | if (err < 0) |
185 | goto release_idr; |
186 | |
187 | d = to_skbmod(*a); |
188 | |
189 | p = kzalloc(size: sizeof(struct tcf_skbmod_params), GFP_KERNEL); |
190 | if (unlikely(!p)) { |
191 | err = -ENOMEM; |
192 | goto put_chain; |
193 | } |
194 | |
195 | p->flags = lflags; |
196 | |
197 | if (ovr) |
198 | spin_lock_bh(lock: &d->tcf_lock); |
199 | /* Protected by tcf_lock if overwriting existing action. */ |
200 | goto_ch = tcf_action_set_ctrlact(a: *a, action: parm->action, newchain: goto_ch); |
201 | p_old = rcu_dereference_protected(d->skbmod_p, 1); |
202 | |
203 | if (lflags & SKBMOD_F_DMAC) |
204 | ether_addr_copy(dst: p->eth_dst, src: daddr); |
205 | if (lflags & SKBMOD_F_SMAC) |
206 | ether_addr_copy(dst: p->eth_src, src: saddr); |
207 | if (lflags & SKBMOD_F_ETYPE) |
208 | p->eth_type = htons(eth_type); |
209 | |
210 | rcu_assign_pointer(d->skbmod_p, p); |
211 | if (ovr) |
212 | spin_unlock_bh(lock: &d->tcf_lock); |
213 | |
214 | if (p_old) |
215 | kfree_rcu(p_old, rcu); |
216 | if (goto_ch) |
217 | tcf_chain_put_by_act(chain: goto_ch); |
218 | |
219 | return ret; |
220 | put_chain: |
221 | if (goto_ch) |
222 | tcf_chain_put_by_act(chain: goto_ch); |
223 | release_idr: |
224 | tcf_idr_release(a: *a, bind); |
225 | return err; |
226 | } |
227 | |
228 | static void tcf_skbmod_cleanup(struct tc_action *a) |
229 | { |
230 | struct tcf_skbmod *d = to_skbmod(a); |
231 | struct tcf_skbmod_params *p; |
232 | |
233 | p = rcu_dereference_protected(d->skbmod_p, 1); |
234 | if (p) |
235 | kfree_rcu(p, rcu); |
236 | } |
237 | |
238 | static int tcf_skbmod_dump(struct sk_buff *skb, struct tc_action *a, |
239 | int bind, int ref) |
240 | { |
241 | struct tcf_skbmod *d = to_skbmod(a); |
242 | unsigned char *b = skb_tail_pointer(skb); |
243 | struct tcf_skbmod_params *p; |
244 | struct tc_skbmod opt = { |
245 | .index = d->tcf_index, |
246 | .refcnt = refcount_read(r: &d->tcf_refcnt) - ref, |
247 | .bindcnt = atomic_read(v: &d->tcf_bindcnt) - bind, |
248 | }; |
249 | struct tcf_t t; |
250 | |
251 | spin_lock_bh(lock: &d->tcf_lock); |
252 | opt.action = d->tcf_action; |
253 | p = rcu_dereference_protected(d->skbmod_p, |
254 | lockdep_is_held(&d->tcf_lock)); |
255 | opt.flags = p->flags; |
256 | if (nla_put(skb, attrtype: TCA_SKBMOD_PARMS, attrlen: sizeof(opt), data: &opt)) |
257 | goto nla_put_failure; |
258 | if ((p->flags & SKBMOD_F_DMAC) && |
259 | nla_put(skb, attrtype: TCA_SKBMOD_DMAC, ETH_ALEN, data: p->eth_dst)) |
260 | goto nla_put_failure; |
261 | if ((p->flags & SKBMOD_F_SMAC) && |
262 | nla_put(skb, attrtype: TCA_SKBMOD_SMAC, ETH_ALEN, data: p->eth_src)) |
263 | goto nla_put_failure; |
264 | if ((p->flags & SKBMOD_F_ETYPE) && |
265 | nla_put_u16(skb, attrtype: TCA_SKBMOD_ETYPE, ntohs(p->eth_type))) |
266 | goto nla_put_failure; |
267 | |
268 | tcf_tm_dump(dtm: &t, stm: &d->tcf_tm); |
269 | if (nla_put_64bit(skb, attrtype: TCA_SKBMOD_TM, attrlen: sizeof(t), data: &t, padattr: TCA_SKBMOD_PAD)) |
270 | goto nla_put_failure; |
271 | |
272 | spin_unlock_bh(lock: &d->tcf_lock); |
273 | return skb->len; |
274 | nla_put_failure: |
275 | spin_unlock_bh(lock: &d->tcf_lock); |
276 | nlmsg_trim(skb, mark: b); |
277 | return -1; |
278 | } |
279 | |
280 | static struct tc_action_ops act_skbmod_ops = { |
281 | .kind = "skbmod" , |
282 | .id = TCA_ACT_SKBMOD, |
283 | .owner = THIS_MODULE, |
284 | .act = tcf_skbmod_act, |
285 | .dump = tcf_skbmod_dump, |
286 | .init = tcf_skbmod_init, |
287 | .cleanup = tcf_skbmod_cleanup, |
288 | .size = sizeof(struct tcf_skbmod), |
289 | }; |
290 | |
291 | static __net_init int skbmod_init_net(struct net *net) |
292 | { |
293 | struct tc_action_net *tn = net_generic(net, id: act_skbmod_ops.net_id); |
294 | |
295 | return tc_action_net_init(net, tn, ops: &act_skbmod_ops); |
296 | } |
297 | |
298 | static void __net_exit skbmod_exit_net(struct list_head *net_list) |
299 | { |
300 | tc_action_net_exit(net_list, id: act_skbmod_ops.net_id); |
301 | } |
302 | |
303 | static struct pernet_operations skbmod_net_ops = { |
304 | .init = skbmod_init_net, |
305 | .exit_batch = skbmod_exit_net, |
306 | .id = &act_skbmod_ops.net_id, |
307 | .size = sizeof(struct tc_action_net), |
308 | }; |
309 | |
310 | MODULE_AUTHOR("Jamal Hadi Salim, <jhs@mojatatu.com>" ); |
311 | MODULE_DESCRIPTION("SKB data mod-ing" ); |
312 | MODULE_LICENSE("GPL" ); |
313 | |
314 | static int __init skbmod_init_module(void) |
315 | { |
316 | return tcf_register_action(a: &act_skbmod_ops, ops: &skbmod_net_ops); |
317 | } |
318 | |
319 | static void __exit skbmod_cleanup_module(void) |
320 | { |
321 | tcf_unregister_action(a: &act_skbmod_ops, ops: &skbmod_net_ops); |
322 | } |
323 | |
324 | module_init(skbmod_init_module); |
325 | module_exit(skbmod_cleanup_module); |
326 | |